Electric Vehicle Battery Load Emulator Circuit

The present invention relates to an electrical circuit that emulates a battery and, in particular, to an electrical circuit that emulates a battery as a load for a battery charging device, e.g., a battery charging device for a battery of or for an electric vehicle.

Batteries, and in particular high-capacity rechargeable batteries, are coming into increased use as more and more devices and equipment is changing over from fossil fuel to electric power. A prime example thereof is the electric vehicle (herein “EV”) which is completely powered by a high-capacity rechargeable battery and which is steadily gaining market share in vehicles produced and sold as a result of government mandates and financial incentives. To further that governmental goal, governments are encouraging, mandating and subsidizing the installation of vehicle charging stations to create an infrastructure to support the use of electric vehicles.

As millions of EVS come into use, hundreds of thousands of electric vehicle charging stations will be needed to meet the demand for charging the batteries of those EVS. Each of those charging stations will have at least one and likely more than one battery charger, and each will likely be configured for charging electric vehicles produced by different manufacturers and/or to different charging and/or battery standards. Moreover, one can imagine battery charging facilities wherein plural or multiple EV batteries of different kinds could be charging at the same time and could require different levels of voltage and/or current while charging.

This will almost certainly require that such battery charging devices meet certain standards for configuration and for battery charging protocols. As a result, a means to test the functioning and performance of such charging devices will be needed and that will necessitate that there be a battery or its equivalent for such unit to be tested with. Charging an actual EV battery will not likely provide a suitable or practical test configuration.

Conventional test loads typically include banks of power dissipating resistors that are switched into and out of circuit to provide a desired load resistance. Such test loads are resistive and so the terminal voltage and the current flowing therethrough are related by Ohm's Law, which is nothing like the characteristic of a battery whose terminal voltage, a DC voltage, does not change by a large amount as the current, e.g., charging current, applied thereto increases and decreases; in other words, a battery approximates a constant voltage load over a range of current levels. Thus, conventional test loads are not suitable representations of a battery for use in testing of a battery charger.

With regard to electric vehicle batteries, which operate at a very high terminal voltage, e.g., about 350-450 VDC and about 750-900 VDC, and which can be charged at relatively high currents, e.g., up to about 600-650 amperes, stringent demands are placed upon devices for testing and evaluating the charging devices, e.g., DC charging stations, for EV batteries and vehicles containing such batteries. It is noted that while a manufacturer of an EVSE (Electric Vehicle Supply Equipment) charging device may advertise their chargers can operate at up to 500 VDC or up to 1000 VDC, as a practical matter the terminal voltage of an EV battery is typically around 380 VDC, and so the ranges ago are believed to be sufficient for battery emulatorwhen emulatoris employed for emulating an EV battery. It is also noted that while an EV manufacturer may advertise its EV battery as being capable of being charged at up to 900 amperes, 600-650 amperes is likely a more realistic level; in any event, the current capacity of battery emulatormay be increased or decreased by adding as many additional loadsas are needed to accommodate the desired current carrying capacity.

Applicant believes there may be a need for an electrical circuit that emulates a battery, i.e. that acts electrically similarly to a battery being charged, suitably for use in testing a battery charging device, e.g., a DC battery charger. Further, Applicant believes that need also applies regarding chargers for electric vehicles and their batteries.

Accordingly, an electrical circuit that emulates a battery when being charged may comprise: first and second terminals configured to have a battery charging device connected thereto; a regulator circuit connected to the first and second terminals including: a voltage sensing circuit connected to the first and second terminals for sensing the voltage therebetween and providing at an output thereof a voltage that is proportional to the voltage between the first and second terminals; a comparator circuit having first and second input terminals, the first input terminal being connected to the output of the voltage sensing circuit and the second terminal being connected to a reference voltage, the comparator circuit having an output at which an output signal responsive to the difference between the output of the voltage sensing circuit and the reference voltage; a controllable load circuit connected to the first and second terminals and including a controllable element that is responsive to the output signal from the comparator circuit for causing a current proportional to the output signal to flow between the first and second terminals; whereby the current flowing in the controllable load circuit is controlled thereby to tend to maintain the voltage between the first and second terminals at a voltage that is proportional to the reference voltage.

An electrical circuit that emulates a battery of or for an electric vehicle when being charged may comprise: first and second terminals configured to have a battery charging device connected thereto; a regulator circuit connected to the first and second terminals including: a voltage sensing circuit connected to the first and second terminals for sensing the voltage therebetween and providing at an output thereof a voltage that is proportional to the voltage between the first and second terminals; a comparator circuit having first and second input terminals, the first input terminal being connected to the output of the voltage sensing circuit and the second terminal being connected to a reference voltage, the comparator circuit having an output at which an output signal responsive to the difference between the output of the voltage sensing circuit and the reference voltage; a controllable load circuit connected to the first and second terminals and including a controllable element that is responsive to the output signal from the comparator circuit for causing a current proportional to the output signal to flow between the first and second terminals; whereby the current flowing in the controllable load circuit is controlled thereby to tend to maintain the voltage between the first and second terminals at a voltage that is proportional to the reference voltage.

In summarizing the arrangements described and/or claimed herein, a selection of concepts and/or elements and/or steps that are described in the detailed description herein may be made or simplified. Any summary is not intended to identify key features, elements and/or steps, or essential features, elements and/or steps, relating to the claimed subject matter, and so are not intended to be limiting and should not be construed to be limiting of or defining of the scope and breadth of the claimed subject matter.

In the Drawing, where an element or feature is shown in more than one drawing figure, the same alphanumeric designation may be used to designate such element or feature in each figure, and where a closely related or modified element is shown in a figure, the same alphanumerical designation may be primed or designated “a” or “b” or the like to designate the modified element or feature. Similar elements or features may be designated by like alphanumeric designations in different figures of the Drawing and with similar nomenclature in the specification. As is common, the various features of the drawing are not to scale, the dimensions of the various features may be arbitrarily expanded or reduced for clarity, and any value stated in any Figure is by way of example only.

Electric vehicle battery chargers, i.e. DC battery chargers, are complex charging devices that typically “work with” many different vehicle batteries and can take into account temperature, battery state of charge, battery voltage level, and the like, and such chargers often “communicate” with the vehicle which communicates battery characteristics, desired battery charging parameters, e.g., a “target” charging current, full charge voltage, and/or rates of current ramping up and down, e.g., 10 amperes per second or 20 amperes per second; the EV battery charger often may set its own limits on charging parameters.

EV DC chargers typically have two operating modes: one for a nominal 400 VDC operation (in which voltage can reach up to less than 450 VDC), and a second for a nominal 800 VDC operation (in which voltage can reach up to less than 900 VDC). These are expected voltage ranges that EV charging devices are designed to accommodate. During charging of an actual battery, the EV charger may experience transients from vehicle equipment operation, e.g., operation of heaters and/or air conditioners, a radio or entertainment system, a GPS and other equipment and features, and so the EV charger is typically designed to accommodate such transients that are caused with an actual EV battery in a real-world situation; these changing load transients only cause voltage transients that are of short duration and small amplitude relative to the voltage of the EV battery.

EV chargers can, however, mis-react to transient changes in the load which is supposed to be a constant voltage device, e.g., a battery, when the transient is not a transient of the sort expected in a real-world battery charging situation. If the charger “senses” that the load, e.g., the test load, doesn't “look like” a real-world battery, as would be the case if the load were banks of switchable resistors which do not resemble a battery load, it may simply discontinue the charging. In addition, other smaller “non-battery-like” changes may be perceived by the charger to indicate that it is being tested and is not charging a “real battery,” which is not desirable.

is a schematic diagram of an example embodiment of an electrical devicefor emulating a battery being charged. A battery, e.g., a battery for an electric vehicle, is a direct current (DC) device that has the terminal characteristic of being a substantially constant voltage device when being discharged and when being charged. The battery terminal voltage, i.e. the battery voltage, does change slightly as a function of the state of charge of the battery and of the level of current being withdrawn from the battery in discharge and the level of current being applied to charge the battery, but it is essentially a constant-voltage load on the battery charger.

In considering the description herein, if the reader can avoid the tendency to think of a battery in its common usage of supplying electrical power to a load and therefore being a constant voltage source that can provide what ever current a load may require, and to think of the battery emulatornot as a battery per se, but as a load that responds by accepting whatever “charging” current may be provided by the EVSE charger.

For EVS and EV batteries, the charging device EVSE tends to operate as DC current source that provides a controllable DC current to charge the vehicle battery, whether that battery is being charged while in the vehicle or is being charged apart from a vehicle. Charger of current source EVSE is illustrated in the Drawing by a circle having an arrow therein indicating the direction of the current it provides. Chargers EVSE are programmed to provide particular current profiles for properly charging EV batteries and an emulatorfor an EV battery must accept the current provided by charger EVSE while maintaining a substantially constant terminal voltage, thereby to emulate the behavior of an actual EV battery.

Emulatorincludes a regulator circuitthat acts to conduct current as necessary to maintain the terminal voltage DC+of emulator(relative to ground or DC−) substantially constant while regulatorabsorbs varying levels of current from charger EVSE. The current that regulatoritself can absorb is limited, however, and that limit may be less than what may be required for testing a given EVSE charger. In that instance, one or more additional load elements, e.g., resistive load elements, can be connected into and out of the circuitry of emulatorso that the current that regulatoris required to absorb to maintain voltage DC+at its desired voltage remains within the current carrying capacity of regulatorirrespective of variations of the total current provided by charger EVSE. Embodiments with 15-20 additional load elementshave been configured, e.g., with appropriate heat sinks, and operate without problems.

The speed of response of regulatoris sufficiently fast that battery emulatoris well able to handle, e.g., by changing the current it is conducting, the ramping up and ramping down of charging current that is induced by the EV charging device. Even though the ramping up of the charging current caused by the EV charger working to increase that current may require that several additional loadsbe connected one after another in sequence, each will involve a current transient that is smaller than the current that regulatorconducts, and so each will in turn be counteracted quickly and effectively, e.g., with a voltage change at terminals DC+ and DC− that is sufficiently small, e.g., typically less than about five volts, which is too small to affect the operation of the charging device or its working to ramp up the charging current. In effect, the charging device is seeing in emulatorwhat appears to be an about 380-400 VDC battery which is the voltage the charging device is expecting to occur.

Regulator circuit, however, is relatively fast acting for changing the level of current it is carrying and so it is well able to counteract the load transients generated by switching additional loadsin and out of circuit in battery emulator. As a result, what starts as a fast change in load current transient caused by changing the load, e.g., by adding or removing a load, is essentially immediately counteracted by regulatorchanging the current it is carrying by substantially an equal and opposite amount. As a result, the effect of those counteracting transients within emulatorproduces a substantially reduced and much smaller, and typically inconsequential, transient at the terminals DC+ and DC− of battery emulator.

Emulatorincludes a controllerthat monitors the current being absorbed by regulatorto maintain regulatorwithin its operating limits of current. In particular, as that current in regulatorincreases, controllerswitches one or more additional loadsinto the circuit such that regulatorremains within its operating limits and as that current decreases, controllerswitches one or more additional loadsout of the circuit such that regulatorremains within its operating limits.

Resistive loads alone switched into and out of a battery emulator would not emulate battery behavior because when switched they introduce discrete rapid changes, e.g., essentially step increases and decreases, in the current conducted by emulatorwhich can affect its terminal voltage DC+. However, Applicant's inventive arrangement overcomes those undesired characteristics. Specifically, regulatorin conjunction with controllerrespond relatively rapidly to counter the abrupt change in current that would occur from a resistive load alone because regulatorabsorbs and/or releases a current that is substantially equal to and opposite to the current change caused by switching in and/or out the additional loadswhich are resistive loads.

EV battery emulatoralso includes a substantial capacitor C, e.g., over 1 micro-Farad or larger, typically about 20 μF in the example embodiment, but could be as large as a milli-Farad, connected across its input terminals DC+ and DC− which absorbs smaller rapid changes in current level while regulatoradjusts its operating point to maintain terminal voltage DC+ at the desired level. A resistor or resistance RP, which may be a small resistor RP, e.g., a resistor of low ohmic value, or may be provided in whole or in part by wiring and/or connector resistance, generates a small voltage change that aids regulatorto respond to changes in the level of current being supplied by charger EVSE.

In the illustrated example embodiment, with the desired emulated battery voltage DC+at about 400 VDC, each additional loadis capable of carrying a maximum current of slightly above 4 amperes when connected. Therein, regulatorcould suffice if capable of carrying a current of up to about 4 amperes using about 100% of its range, however, regulator 20 is preferably configured to have a current capacity of about 8 amperes, or about twice the current capacity of each additional load. With that configuration, regulatorcan operate entirely within its linear range when a loadis switched in circuit (connected) or is switched out of circuit (disconnected), and suitable set points for regulatorat about 25% and 75% of its maximum current appear to be a suitable set point for controllerto control adding and removing an additional load.

Also in that configuration, controllermay determine when to switch an additional loadin or out of emulator circuitby responding to the measured current conducted by regulatoror by measuring a voltage related to that current.

Controllermay, and preferably does, include a microprocessor, microcontroller, and/or other processor that can be controlled and/or programmed for controlling the operation and characteristics of battery emulator. It is noted that controllermay be referred to herein as a microprocessor, a microcontroller, and/or a processor. Such processorscommonly include one or more analog-to-digital converters, one or more digital-to-analog converters, a reference voltage generator, and various inputs configured to receive analog or digital signals and various outputs configured to provide analog and/or digital signals. Control inputs to controllercan control, e.g., the value of the reference voltage VDAC provided to regulatorincluding programming VDAC over a period of time and/or over various testing and simulation sequences, and/or the states of connection of additional loads.

Certain EV charging stations may not operate properly when connected to an electric vehicle or a battery emulator if there is no voltage present that is representative of a battery being present. To avoid battery emulatorfrom seeming to not be a battery to an EV charging station, pre-charge emulator circuitmay be provided.

Pre-charge emulatormay comprise a source of electrical voltage PSrepresenting a battery to be charged and a diode Din series therewith that are connected across the input terminals of battery emulator. For example, the voltage provided by power source PSmay be in the range of about 250 VDC to 400 VDC for an emulator for emulating a 400 VDC battery, and similar ranges of voltage scaled for representing batteries to be charged of different voltages can be utilized.

Voltage source PSneed not have capacity to provide a substantial current, as it only need provide a DC voltage representative of a battery to be charged. Typically, PSmay only need to be able to provide a few hundred milliamperes or less. Power source PSmay be, e.g., a power supply, a battery, a DC convertor and/or voltage regulator, or any other suitable source of DC voltage. Diode Dprevents current from the charging station from flowing into power source PS. While pre-charge emulatoris not necessary for operation of battery emulator circuit, pre-charge emulatoris preferably included therein.

is a schematic electrical circuit diagram of an example embodiment of a regulator circuitfor use in the example embodiment of the battery emulatorof. Regulator circuitincludes: a voltage sensing circuit, a comparator circuit, an amplifierand a controllable load circuit, R. Integrated circuit amplifiers, operational amplifiers, instrumentation amplifiers, and other amplifiers, have inverting inputs (−) wherein their output voltage changes in a direction opposite to the direction of input voltage signals applied at its inverting (−) input and have non-inverting inputs (+) wherein their output voltage changes in the same direction as the direction of input voltage signals applied at its non-inverting (+) input.

Voltage sensing circuitincludes an operational amplifier U, e.g., an integrated circuit Uhaving substantial open circuit gain which is reduced by feedback to be a desired value of gain determined by the values of resistors Rand R. In one example embodiment, with amplifier Uin a non-inverting configuration, the ratio R/Ris about 1/100 thereby providing a gain of about 0.01. If the desired emulated battery voltage +DC is 400 VDC, then the output of voltage sensing circuitis about +4 VDC and any deviation therefrom represents an “error” signal representative of a deviation of voltage +DC from its programmed and desired voltage.

A diode DZmay be connected to the junction of Rand Rand the inverting input of amplifier Uto provide protection against excessive voltage being applied at that input. Diode DZis, e.g., a Zener diode or other voltage limiting circuit element, that tends to limit voltage. In normal operation, DZis not conducting; in case of excessive positive voltage, diode DZlimits the voltage thereat to a value that is between the power supply voltages that are applied to operate the amplifier integrated circuit. If the amplifier power supply is about plus and minus 12-15 VDC relative to ground (DC−), then DZcan limit voltage to about 12 VDC and in case of excessive negative voltage, DZlimits the voltage to about-12 VDC.

Comparator circuitincludes an operational amplifier U, e.g., an integrated circuit Uhaving substantial open circuit gain which is reduced by feedback to be a desired value of gain determined by the values of resistors R, Rand R. The non-inverting input of amplifier Ureceives a reference voltage VDAC via resistor Rwhich determines the voltage to which +DC will be regulated. For example, if the reference voltage VDAC is +4 VDC as in the illustrated example, then +DC will be +4/0.01 =+400 VDC, i.e. the desired voltage of battery emulator.

The reference voltage VDAC for regulatoris provided by a reference source of which many different kinds may be employed; examples include a voltage reference diode such as a Zener diode, a voltage regulator integrated circuit, a reference output from a microprocessor or microcontroller, and the like. In the illustrated preferred embodiment, reference voltage VDAC is provided, e.g., by a digital-to-analog converter DAC so that the reference voltage can be controlled, e.g., under control of controllerwhich includes the digital-to-analog converter DAC and/or external signals and/or commands.

In addition to providing a comparator, amplifier Ualso serves as an inverting amplifierwhose gain is determined by the ratio of Rto the effective resistance of parallel resistors Rand R. In one example embodiment, that ratio R/(R|R) is configured to provide an effective overall gain of about two. Thus, amplifier Userves a dual function in this example embodiment.

One example of a controllable load circuitincludes a load resistor Rin series with a controllable element Qconnected across the input of emulator, e.g., between its first and second terminals +DC and −DC for conducting a controllable current therebetween that is at least a portion of the “charging” current being provided by a battery charger EVSE. The controllable element, e.g., a transistor Q, is configured with an operational amplifier Uwhich is in a unity-follower configuration controlled by resistors R, Rwherein capacitor Ctends to smooth the rate of change of current through R, Q. Unity follower Uprovides an output voltage at the junction of transistor Qand resistor RS that is equal to the voltage at the non-inverting input of amplifier U, i.e. it exhibits a voltage gain of +.

Controllable element Qhas a control terminal, e.g., the gate of a field-effect transistor (FET) Q, coupled to the output of the amplifier U, e.g., an operational amplifier U, and having a controllable conduction path between output terminals, e.g., between the source and drain of FET Q. Other controllable devices, e.g., junction transistors and other suitable semiconductor devices, may be employed as the controllable element. The controllable element in this instance will need to be able to operate with the highest terminal voltage of battery emulator, e.g., the terminal voltage of the battery charger connected to battery emulator, which can be 400 VDC, or 800 VDC, or 1000 VDC, depending upon the charger, and will also need to carry the maximum current of regulatorwhich could beoramperes, in the illustrated embodiment, or higher.

Where high current carrying capacity is needed, e.g., more than one FET driver and FET Qcan handle, plural controllable loadscan be employed in parallel, and the total current will be accurately shared among the parallel loadsbecause of the configuration of the unity-follower FET driver circuit and the current sensing and controlling resistor RS of each. Up tosets thereof in parallel have been tested without problem. Using plural controllable loadsalso helps to allow the heat generated thereby to be spread out over a larger physical area, e.g., by power resistors mounted on heat sinks (heat dissipaters) that can include air or liquid heat removal devices, and/or other cooling arrangements.

Accordingly, the current that flows through resistor Rand transistor Qof the controllable loadof regulatoris equal to the voltage at the non-inverting input to amplifier Udivided by the resistance of current sensing resistor RS. Thus, the FET driver circuit including Uand Qconverts the voltage at the non-inverting input of amplifier Uinto a proportional current flowing through FET Qand resistor RS. The resistance of current sensing resistor RS may be any convenient value, but is typically one ohm or less. In the illustrated example, the resistance of RS is about 200 milli-ohms.

In each of the foregoing embodiments, the resistors Rand resistive loadsinclude power resistors that are configured to dissipate the heat that is generated by the part of charger EVSE current that flows therein. Often such high power resistors include integrated heat conductive bodies that provide for removal of heat and/or that may be or are coupled to heat sinks, air cooling devices, water cooling devices, and the like, to have a power dissipation capability that is consistent with the maximum power that can be dissipated in each such power resistor. For example, where resistor Rcan carry as much as about 8 amperes in a simulated 400 VDC charging environment, that resistor R6 is rated to safely dissipate 2400 watts (2.4 kW) or if R6comprises plural resistors R6, their aggregated power rating is 2400 watts.

Where battery emulatoris part of an item of test equipment of a general nature for testing a wide range of different battery chargers, e.g., EV battery chargers, current and power capacities of regulatorand the numbers of additional loadsand their power handling capacities, will be scaled to accommodate the highest power EV battery charger that could be tested using EV battery emulator. Such scaling may include increasing or decreasing the number and/or kinds of additional load circuits, changing the values of various elements, e.g., the reference voltage VDAC from the DAC and/or the values of the resistors that set the ratio between the terminal voltage DC+of emulatorand the reference voltage VDAC.

is a schematic electrical circuit diagram of an example embodiment of a regulator circuit′ for use in the example embodiment of the battery emulatorof. Regulator circuit′ is functionally equivalent to regulatorpreviously described except that sensing circuit, comparator circuitand amplifierwhich include operational amplifiers Uand Uare replaced by an instrumentation amplifier U′. Instrumentation amplifier U′ is an amplifier that has significant gain that is programmable, and is programmed here, to provide the desired gain and response for regulator′, however, instrumentation amplifiers can have narrower bandwidth than do, e.g., are not as “fast” as, other amplifiers, e.g., operational amplifiers.

Here, instrumentation amplifier U′ is programmed to have a non-inverting gain, e.g., of about two, for providing negative feedback for correcting errors in the voltage +DC of battery emulatorrelative to its desired programmed voltage.

Resistors R, Rperform the same voltage sensing function as described above and controllable load circuitincluding FET driver U, Qfunction as described above. The operation of regulator′ is the same as that of regulatordescribed above. As a result, battery emulatoroperates in the substantially the same way whether regulatoror regulator′ is employed therein.

Further regarding regulatorand additional loads, controllerpreferably responds to the level of current being conducted by regulatorfor determining when to connect an additional loadand/or to disconnect an additional load. When the current being provided from charging device EVSE changes, e.g., increases as when charger EVSE is ramping up, then when the current being conducted by regulatorincreases concomitantly until it approaches its maximum level. Controllerdetects that condition of regulatorand responds by connecting an additional load. The current drawn by additional loadcauses a slight negative transient in the voltage at terminals DC+and DC-of emulatorwhich causes the voltage sensing and comparator circuitry,,of regulatorto reduce the current drawn by controllable loadby an equal amount so that the total of the current drawn by regulatorand the additional loadis substantially the same as the total current immediately prior to the additional loadbeing connected.

As a result, regulatoris always operated within the range of currents over which it can exercise control. Thereby, controlleroperates such that regulatoris always operated within the range of current over which it can exercise control, e.g., between the minimum level of 0% and the maximum level of% of its current carrying capacity.

Providing a signal representing the current being conducted by regulatorto controllercan be done is several alternative ways. For example, the voltage across current sensing resistor RS is directly related to that current and controllercan monitor that voltage. When, e.g., RS is 200 milli-ohms and the maximum current is about 8 amperes, 100% of current is represented by 1.60 volts (1600 mV) across resistor RS. When, e.g., the high and low current “limits” are set for% and% of maximum current, controllerwould be configured to detect 0.16 v and 1.44 v, respectively, across resistor RS. Alternatively, when, e.g., the high and low current “limits” are set for 25% and 75% of maximum current, controllerwould be configured to detect 0.40 v and 1.20 v, respectively.

Alternatively, the current flowing in regulatorcan be monitored by monitoring the voltage at the connection of the source terminal of FET Qand load resistor Rwhich is labeled VREG in. Consider the case where the voltage of the battery being emulated is 400 VDC. When, e.g., the high and low current “limits” are set for 10% and 90% of maximum current, controllerwould be configured to detectv andv, respectively, at point VREG. Alternatively, when, e.g., the high and low current “limits” are set for 25% and 75% of maximum current, controllerwould be configured to detect 300 v and 100 v, respectively.

Detection of voltage levels by controllermay be accomplished by setting up thresholds to be detected at analog inputs thereto or internally thereto after the analog voltage across RS or at VREG is converted by an analog-to-digital converter of controllerand is detected digitally therein. Alternatively, analog comparators may be employed for voltage detection.

Preferably, the value of resistor Ris made to be less than the resistance of the additional loadsthereby providing additional current range for regulatorthan is needed to offset any additional loadbeing connected or disconnected. In one embodiment of the example battery emulatorillustrated, resistor Ris 48 ohms and additional loadresistors are 96 ohms. Said differently, each additional loaddraws about 4.16 amperes at an emulated battery voltage DC+of 400 VDC, and regulatorcan draw up to about 8.3 amperes.